Means for preventing oil fog from air pumps



July 14, 1936. J ERUNG 2,047,728

MEANS FOR PREVENTING OIL FOG FROM AIR PUMPS Filed June 14, 1934 9 0b 5 22 N J F/GJ.

- I @502 Jog 54, 7

Patented July 14, 1936 ,lUNl-TED" STATES PATENT OFFICE Y Y Sven Johan Erling; Noekeby, Sweden, assignor to The De Laval Separator Company, New York, N. Y.,'a corporation of New Jersey Application June "14, 1934, Serial Newman 1 In Sweden June 22, 1933 8, Claims. (01. 230-206) It is well known that the lubricant used in air pumps is atomized and carried off by the generated air current. In case the pump is erected in a house and is not provided with an exhaust pipe to the atmosphere the oil fog which forms is highly objectionable. The oil particles in the air current are very small and bowl-shaped, and the attempts made heretofore to remove them have not been successful.

Itis the object of the present invention to eliminate the oil particles from the air current beforethe air leaves the pump. r H

' I have found that if the oil particles are forced under pressure through a sufficiently narrow'slit the oil precipitates on the outer side of the slit. The width of the slit shouldnot exceed about onetenth of 'a millimeter. The present invention is based on this discovery and is shown in one suitable embodiment on the accompanying drawing, wherein Fig. 1 is a longitudinal sectional view, of an air pump embodying my invention.

Fig. 2 is a detail view of the valve housing and the valve controlling outflow of oil therefrom.

Fig. 8 is a detail view of the valve controlling flow of air from the pump to the air discharge passage.

Fig. 4 is a cross section on the line 4-4 of Fig. 1.

The pump may be of any known construction. In the drawing one known form of pump to which my invention has been applied is shown. On the forward end of the pump shaft I5 is a crank pin 20 which, through a ball bearing 2|, engages the hub of a disc I, imparting thereto and to a ring-shaped member H4 integral therewith an oscillatory movement. The ring I I4 has at one point in its circumference a out which straddles a radial partition 22 between the stationary cylindrical walls l8 and i9. Oscillation in the direction shown by the arrow :2: draws in air at port I! and forces air out at port l6 connected by a passage, not shown, with the space inside the inner stationary ring l9. Both the spaces inside and outside of ring H4 act as pumps. It will be understood that the described construction of pump is no part of my invention.

Rotating with the pump shaft I5 is a disc 2 against which air outflowing from the oscillating piston H4 through the center of the stationary ring l9 impinges. In the specific form of pump shown the disc 2 is mounted eccentric to the crank pin but concentric with the shaft IS. The disc 2 may be formed with an eccentric cup to fit a concentric hub on the crank pin, or, as shown,

the disc may'be. mounted on an eccentric hub 23 on the crank pin. V i

As outfiowing air from the center of the pump impinges against the disc2, large oil drops are v removed by the disc and are thrown against'the pump housing, whence they flow back into the oil bath 3.

The central exhaust opening 5 in the cover 4 is normally closed by a valve 6 which rests on a seat 1 in the valve housing 8. Valve 6 comprises 10 a solid central part from which extend a number of spring arms 6' having inturned ends which rest against the valve housingj the spring arms tendingto hold the central part against the seat 1, that is, to hold the valve closed; the valve, however, being unseated by the pressure of air flowing from the pump. Asmall quantit of oil can gather in the valve housingkand then flows out through the opening 9 whenthe pump stops and the valve l0 opens. The air current enters 20 thechamber i I, which is provided with a screen l2 having openings for the air. The screen prevents any oil drops which are possibly carried by the air pastthe said disc 2 from flowing out with the air. The air streams out from chamber ll 25 through an opening I3.

When the pump is started the exhaust valve 6 is closed and the valve l0 covering the opening 9 is open. The air current which is generated when the pump starts working will rush out this 30 latter way, but the valve I0 is then forced down and closes the opening. The pressure in the cover 4 increases until the valve 6 is opened and forms between it and the valve seat 1 a slit of the restricted width above specified. The pressure ex- 35 erted on the valve by the spring and the quantity of air streaming out must be determined the v one with regard tothe other, so as not to make the slit too wide. Owing to the solid matters which may be brought out with the air it is not suitable to provide a fixed slit.

More than one screen, with non-aligning openings, may be provided, to more absolutely insure against the escape of any oil drops which may possibly still be retained by the air entering chamber il.

What I claim and desire to protect by Letters Patent is:

1. In an air pump, the combination of means forming a passage through which generated currents of air escape, said passage having an air admission opening and an air exhaust opening, and a member positioned at the air admission opening and spaced therefrom so as to form a narrow slit not exceeding about one-tenth of a millimeter in width and through which air may flow out and adjacent to which oil particles may precipitate.

2. In an air pump, the combination of means forming a passage through which generated currents of air escape, said passage having an air admission opening and an air exhaust opening, and a member positioned at the air admission opening and adapted to be spaced therefrom to form a narrow slit through which air may flow out and adjacent to which oil particles may precipitate, said member being movable relatively to said air admission opening by the pressure of outflowing air so as to maintain said slit open for passage of air and escape of oil particles during the operation of the pump.

3. In an air pump, the combination of means forming a passage through which the generated currents of air escape, said passage having an air admission opening and an air exhaust opening, and a spring actuated valve normally closing said opening and which is adapted to be forced ofi its seat to provide a narrow slit for passage of air and escape of oil particles.

4. In an air pump, the combination of a cham her for passage of outflowing air, provided with an air inlet and an air outlet, a valve housing at the inlet end of the chamber having an air inlet, and a valve, within said housing, affording a restricted opening for flow of air and oil particles, the housing forming a receptacle for oil which is carried through said restricted opening with the air andiprecipitates.

5. In an air pump, the combination of a chamber for passage of outflowing air, provided with an air inlet and an air outlet, a valve housing, at the inlet end of the chamber having an air inlet, and a valve, within said housing affording a restricted opening for flow of air and oil particles, the housing forming a receptacle for oil which is carried through said restricted opening with the air and precipitates, said housing having an opening for outflow of precipitated oil and a valve which closes said opening under the pressure of air discharged by the pump and which is adapted to open to discharge accumulated oil as the pump slows down or stops.

6. In an air pump, the combination of means forming a passage through which the generated currents of air'escape, said passage having an air admission opening and an air exhaust opening, a member positioned at the air admission opening and spaced therefrom so as to form a narrow slit through which air is adapted to outflow and adjacent to which oil particles are adapted to precipitate, and a rotatable disc in front of said air admission opening and against which impinges air outflowing from the pump and which is adapted to throw off any oil which adheres thereto and is not carried around and beyond it with the air.

7. In an air pump, the combination of means forming a passage through which generated currents of air escape, said passage having an air admission opening andan air exhaust opening, a member positioned at the air admission opening and spaced therefrom so as to form a narrow slit through which air may flow out and adjacent to which oil particles may precipitate, and a screen positioned in said passage'and provided with one or more openings, said screen being adapted to collect any oil drops which may be carriedby the air that impinges against the screen.

8. In an air pump, the combination of a rotary oil deflecting and throwing member and air escape permitting means including an annular seat and a member spring pressed toward said seat but movable therefrom by air pressure during operation of the pump to provide a narrow slit through which air may flow outward and adjacent to which oil particles may precipitate.

SVEN JOI-IAN ERLING. 

